This invention relates to the production and transport of pelleted material. In one of its aspects it relates to underwater pelleting systems and the transporting of pellets formed underwater. In another of its aspects, it relates to a method for cooling pellets discharged from an underwater pelleter. In another of its aspects it relates to the compounding of blowing agent into polymeric material with extrusion and cooling of the pelleted compositions. In another of its aspects it relates to the diversion of flow in the transporting of pelleted material.
Many processes relating to the compounding of polymeric resinous material with various additives, the extrusion and underwater pelleting of these cmpositions and the transportation of the pellets produced are well known in the art. Upon actually assembling a system for compounding a blowing agent with a polymeric resin to produce a pelleted product without activating the blowing agent in the pellets it was discovered that such an integrated process required manipulations which are surprising in light of the known prior art. Some of these manipulations are applicable to general systems for the pelleting and transport of pelleted materials.
It is therefore an object of this invention to provide an integrated process for compounding additives, particularly blowing agents, with polymeric resins, extruding and pelleting the compositions, and providing cooled, pelleted product, that particularly in the case of pellets containing blowing agent are not activated to expand during the process. It is also an object of this invention to provide a general process for extruding and transporting pellets. It is another object of this invention to provide a method for cooling pellets which are extruded underwater. It is still another object of this invention to provide a control system in the transporting of pelleted material in which flow can be diverted automatically from a product collection vessel to an off-grade pellet collection vessel.
Other aspects, objects and various advantages of this invention will become apparent upon reading this disclosure and the appended claims in conjunction with the drawing.